Functional ion channel confirmed in extracellular vesicles – no longer just passive messengers.
Extracellular vesicles (EVs) are getting a lot of – rightfully deserved – attention right now since they help cells communicate by transferring proteins, lipids, and RNA. But beyond their role as cargo carrier, do EVs themselves have more functional membrane properties? A recent study published in Nature Communications suggests they do.(1) Researchers identified BKCa (large conductance calcium-activated potassium) channels in EV membranes, to show that EVs aren’t just passive couriers, but actively regulate ion homeostasis and influence recipient cell function.
EVs as Functional Membrane Structures
Ion channels are a staple in cell biology, governing ion flux and electrical signaling in cells, but their role in EVs is largely unexplored. While earlier research has show that EVs may have a more complex role than we first imagined, little was known about their electrophysiological function. This study aimed to bridge that gap by investigating whether EV membranes exhibit measurable ion channel activity and how this impacts their stability and function.
Researchers isolated EVs and confirmed their purity using established positive and negative markers. They then used patch-clamp electrophysiology to assess membrane conductance. The results showed BKCa channel activity in EV membranes.
To confirm BKCa channel identify, the researchers used Anti-KCNMA1 (KCa1.1) (1097-1196) Antibody (#APC-021). This antibody clearly showed BKCa channel expression in EVs (Figure 1), which reinforced their electrophysiological findings. Although there are several other ion channels and transporters present – like CLIC4 (2) – this is the first time functional ion channels have been seen in EVs. The presence of these potassium channels suggests that EVs may influence target cells not only by delivering cargo but also by modulating ionic environments.
Figure 2: BKCa channels in EVs. a Representative Western blot showing the presence of BKCa and protein loading control (Ponceau S) in EVs isolated from plasma of mice (n = 3). Purified EVs from kcnma1+/+ mice (b–e) (shown as green, d) and kcnma1−/− mice (f–i) labeled with pkh67 (green) and anti-BKca (red). Human iPSC-derived cardiomyocytes (hiPSC-CM, j–u) were incubated with EVs isolated from kcnma1+/+ and kcnma1−/− labeled pkh67 (green, l, and r, respectively). hiPSC-CM were loaded WGA (magenta, m, and s) and fixed for immunocytochemical analysis. hiPSC-CM were permeabilized and labeled with anti-BKca antibodies (red, k, and q) and DAPI (blue, j, and p). All images were merged in n (j–m) and t (p–s). o and u are zoomed regions from n and t, respectively. bkca was present in evs isolated from kcnma1+/+ (yellow arrow) but not in kcnma1−/− mice.
Functional Role of BKCa Channels in EVs
Beyond confirming BKCa channel expression in EVs, the study explored their functional consequences. Electrophysiological analysis revealed that BKCa channels contribute to potassium homeostasis in EVs, allowing them to adjust to extracellular ionic shifts. These BKCa channels also influenced the molecular cargo of EVs, particularly microRNAs involved in cardioprotection.
Interestingly, the study found that BKCa channels in EVs have no effect on their uptake by recipient cells, but they do regulate the EVs’ physiological effects once inside. Cardiomyocytes exposed to EVs with BKCa channels coped better with oxidative stress, while those receiving EVs without them were more vulnerable. This suggests that ion channel activity in EV membranes plays a direct role in modulating cellular function
What’s Next for EVs?
This study challenges the idea that EVs are just passive carriers. The discovery of functional ion channels suggests they might directly influence cell excitability, ion balance, signaling, or even metabolism. Beyond that, the findings raise questions about the broader implications of ion channels in EV biology. Do different types of EVs contain distinct ion channels? How does ion channel activity influence EV uptake or signaling in recipient cells? These questions open the door to further investigation into the functional properties of EV membranes.
EV research still has to deal with the difficulties associated with isolating vesicles from structures such as apoptotic bodies and cell debris, along with subsequent identification. But this study, shows that it can be done when the right combination of positive and negative protein markers are in place. High-specificity antibodies, like those used here, help researchers confidently distinguish EVs from other membranous structures.
This work here rewrites the role of EVs. More than molecular couriers, they emerge as electrically active structures capable of reshaping cellular function.
Reference
- S. Sanghvi, D. Sridharan, P. Evans, J. Dougherty, K. Szteyn, D. Gabrilovich, M. Dyta, J. Weist, S. V. Pierre, S. Gururaja Rao, D. R. Halm, T. Chen, P. S. Athanasopoulos, A. M. Dolga, L. Yu, M. Khan, H. Singh, Functional large-conductance calcium and voltage-gated potassium channels in extracellular vesicles act as gatekeepers of structural and functional integrity. Nat Commun 16, 42 (2025). DOI: https://doi.org/10.1038/s41467-024-55379-4.
- V. C. Sanchez, A. Craig-Lucas, C. Cataisson, B. L. Carofino, S. H. Yuspa, Crosstalk between tumor and stroma modifies CLIC4 cargo in extracellular vesicles. J Extracell Biol 2, e118 (2023). DOI: https://doi.org/10.1002/jex2.118.
Print this post
Share this post